diff --git a/pyproject.toml b/pyproject.toml
index fc9b0b2..58c986a 100644
--- a/pyproject.toml
+++ b/pyproject.toml
@@ -47,7 +47,8 @@ dependencies = [
     "mavehgvs==0.6.1",
     "fastapi",
     "starlette",
-    "uvicorn"
+    "uvicorn",
+    "polars<1.38.0"
 ]
 dynamic = ["version"]